1. Field of Invention
The field of invention relates to apparatus that uses the steel drill string attached to a drilling bit during drilling operations used to drill oil and gas wells for a second purpose as the casing that is cemented in place during typical oil and gas well completions. The field of invention further relates to methods of operation of said apparatus that provides for the efficient installation a cemented steel cased well during one single pass down into the earth of the steel drill string. The field of invention further relates to methods of operation of the apparatus that uses the typical mud passages already present in a typical drill bit, including any watercourses in a “regular bit”, or mud jets in a “jet bit”, that allow mud to circulate during typical drilling operations for the second independent, and the distinctly separate, purpose of passing cement into the annulus between the casing and the well while cementing the drill string into place during one single drilling pass into the earth. The field of invention further relates to apparatus and methods of operation that provides the pumping of cement down the drill string, through the mud passages in the drill bit, and into the annulus between the formation and the drill string for the purpose of cementing the drill string and the drill bit into place during one single drilling pass into the formation. The field of invention further relates to a one-way cement valve and related devices installed near the drill bit of the drill string that allows the cement to set up efficiently while the drill string and drill bit are cemented into place during one single drilling pass into the formation.
2. Description of the Prior Art
From an historical perspective, completing oil and gas wells using rotary drilling techniques has in recent times comprised the following typical steps. With a pile driver or rotary rig, install any necessary conductor pipe on the surface for attachment of the blowout preventer and for mechanical support at the wellhead. Install and cement into place any surface casing necessary to prevent washouts and cave-ins near the surface, and to prevent the contamination of freshwater sands as directed by state and federal regulations. Choose the dimensions of the drill bit to result in the desired sized production well. Begin rotary drilling of the production well with a first drill bit. Simultaneously circulate drilling mud into the well while drilling. Drilling mud is circulated downhole to carry rock chips to the surface, to prevent blowouts, to prevent excessive mud loss into formation, to cool the bit, and to clean the bit. After the first bit wears out, pull the drill string out, change bits, lower the drill string into the well and continue drilling. It should be noted here that each “trip” of the drill bit typically requires many hours of rig time to accomplish the disassembly and reassembly of the drill string, pipe segment by pipe segment.
Drill the production well using a succession of rotary drill bits attached to the drill string until the hole is drilled to its final depth. After the final depth is reached, pull out the drill string and its attached drill bit. Assemble and lower the production casing into the well while back filling each section of casing with mud as it enters the well to overcome the buoyancy effects of the air filled casing (caused by the presence of the float collar valve), to help avoid sticking problems with the casing, and to prevent the possible collapse of the casing due to accumulated build-up of hydrostatic pressure.
To “cure the cement under ambient hydrostatic conditions”, typically execute a two-plug cementing procedure involving a first Bottom Wiper Plug before and a second Top Wiper Plug behind the cement that also minimizes cement contamination problems comprised of the following individual steps. Introduce the Bottom Wiper Plug into the interior of the steel casing assembled in the well and pump down with cement that cleans the mud off the walls and separates the mud and cement. Introduce the Top Wiper Plug into the interior of the steel casing assembled into the well and pump down with water under pump pressure thereby forcing the cement through the float collar valve and any other one-way valves present. Allow the cement to cure.